Multistage model rocket



Dec. 1966 v. D. ESTES ETAL MULTISTAGE MODEL ROCKET Filed. Sept. 14, 1964 2 Sheets-Sheet 1 Fig. 2

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MULTISTAGE MODEL ROCKET 2 Sheets-Sheet 2 Filed Sept. 14, 1964 Fig. 3

INVENTORS Vernon D. Estes WiHiomMSimon BY JAM/M K ATTORNEY United States Patent 3,292,302 MULTISTAGE MODEL ROCKET Vernon D. Estes and William M. Simon, Penrose, Colo., assignors to Estes Industries, Inc., a corporation of Colorado Filed Sept. 14, 1964, Ser. No. 396,254 3 Claims. (CI. 46-74) This invention relates to model rockets and more particularly to multistage types of model rockets, it being an object of the invention to provide a novel and improved multistage model rocket having a primary section and one or more booster sections which are interconnected at the beginning of a flight, but which separate during the course of the flight to simulate in a model the actual flight pattern of a prototype multistage rocket.

The invention encompasses a unique, simple construction of a multistage model rocket wherein a primary model rocket and a booster section are interconnected in a tandem alignment to permit the booster section to initiate the first phase of flight and separate from the primary rocket as it burns out, with the flight being continued by the primary model, all in a smoothly coordinated continuous sequence of operation. Accordingly, the invention will be described especially with respect to a twostage-type rocket consisting of the primary section and a booster section, but it is to be understood that constructions and principles herein described may also apply equally well to model rockets having two or more booster sections.

Another object of the invention is to provide a novel and improved construction of a multistage model rocket using conventional cylindrical rocket motors, and wherein such motors are used to facilitate interconnection of the several stages of the rocket in a simple, effective manner, which insures separation of one stage from the other as the motor of the lower stage burns out.

Another object of the invention is to provide a novel and improved two-stage model rocket wherein the primary body section and the booster section are neatly interconnected in tandem with conventoinal cylindrical motors in the sections abutting each other in a manner which is especially adapted to permit the driving motor of the lower stage to build up an ejection pressure as it burns out, and not only assure separation of the stages, but also assure the attainment of a suitable pressure and temperature level at the exhaust of the motor of the upper stage to a degree which is sufficient to positively ignite the upper stage motor as the stages separate, all providing continuing uninterrupted flight of the primary body of the model.

Another object of the invention is to provide a novel and improved multistage model rocket which is especially adapted to be used with standard, commerciallyavailablc types of cylindrical model rocket motors to thereby provide for the amateur model rocketeer, a maximum degree of safety and reliability in flying his models.

Further objects are to provide a novel and improved multistage model rocket which is a simple, neat appearing, especially easy to build and operate and is capable of being lofted to considerable height even when carrying a small parachute or other light load in its body which may be ejected at the peak of its upward flight.

With the foregoing and other objects in view, all of which more fully hereinafter appear, our invention comprises certain constructions, combinations and arrangements of parts and elements as hereinafter described, defined in the appended claims and illustrated in preferred embodiment in the accompanying drawing, in which:

FIGURE 1 is a side elevational view of our two-stage model rocket mounted upon a launching pad as when it is ready for launching into flight.

FIGURE 2 is a diagrammatic sketch to illustrate the nature of the flight of the two-stage model rocket, with the rocket being repetitiously shown at various phases of the flight path, as on the launching pad, in the air when the booster separates from the primary body portion, at the peak of its flight when it comes apart as to release a parachute and during the drop as where it is being lowered by the parachute.

FIGURE 3 is a longitudinal side view of the model rocket illustrated at FIG. 1, but on an enlarged scale and with several of the components being separated to better illustrate their construction.

FIGURE 4 is a longitudinal sectional view of the model rocket illustrated at FIG. 1, but on a further enlarged scale and with portions of the guide fins being broken away to conserve space.

FIGURE 5 is a front end view of the rocket model shown at FIG. 4 to illustrate a preferred arrangement of the guide fins and of the booster.

FIGURE 6 is a side view of the rear or trailing portion of the primary rocket and of the booster of the portion, similar to the showing at FIG. 3, but illustrating more specifically the manner in which the sections will be separated as during flight and with portions of the body being broken away to show parts otherwise hidden from view.

FIGURE 7 is a longitudinal side view of two conventional rocket motors abutted end to end to illustrate specifically the manner in which they are interconnected, preliminary to being used with the two-stage model rocket FIGURE 8 is longitudinal sectional view as taken from the indicated line 8-8 at FIG. 7.

FIGURE 9 is an elevational view of a model rocket similar to FIG. 1, but on a reduced scale and showing a three-stage arrangement.

FIGURE 10 is a side elevational view of a model rocket similar to FIG. 1, but on a reduced scale and showing the components as being modified to provide a small, single stage unit.

Referring more particularly to the drawing, the model rocket R illustrated at FIGS. 1 through 6 has two stages, including the leading, primary section P and the trailing, booster section B. The leading primary section P includes an elongated cylindrical body 15, a rounded nose cone 16 at its leading end and guide fins 17 at its trailing end. The booster section is formed as a short, cyindrical body 18 having a diameter substantially the same as the diameter of the primary body portion 15. It also includes a set of giude fins 19 arranged in a radial array about the body.

These two sections, which will be hereinafter described in detail, are adapted to be interconnected in tandem with the booster section trailing the primary section. Standard types of cylindrical pyro-propulsive motors M and M are carried within each section, as will be hereinafter described. To initiate a flight, the rocket and booster are interconnected and are set upon a launching pad 20 as in the manner illustrated at FIG. 1. In preferred construction, this launching pad includes an upstanding guide wire 21 which is threaded into a sleeve 22 on the primary body section 15, the action of the guide wire being such as to effect an initial vertically directed movement of the toy rocket as it commences its upward flight. Since the model rocket engines are of a pyro-propulsive type, the complete launching equipment will ordinarily include an ignition Wire 24 which is inserted into the exhaust end of the base of the motor booster and into the motor therein for igniting the same.

The flight of a two-stage model rocket is illustrated diagrammatically at FIG. 2. The flight will initiate from the launching pad 20 and the rocket will be first projected upwardly by the booster section B until the motor within chute shroud lines.

the booster section burns out. At that time, the sections will separate, and the primary rocket model will continue to soar upwardly while the booster section B drops to the ground.

The body of rimary section P is preferably made of two parts, which will separate at the apogee of flight, as will be hereinafter described, and a parachute 23 or a streamer or the like will be released from these parts. The parachute will control the descent of the primary rocket model to the earth and will assist the ground observers in locating the model.

The structure of the primary section and the booster section are shown in detail at FIGS. 3, 4 and 5. The primary section P includes the body section 15 which is a thin, cylindrical shell having a length sufficient to house a motor M in its rear portion and to provide space for a folded parachute in its front portion. The inside diameter of the body 15 is adapted to receive a short cylindrical motor M. with a loose sliding fit as hereinafter described. The trailing portion of this main body section 15 carries three or four guide fins 17 which are arranged in a regular array about the body. These fins extend behind the trailing edge of this body 15 in a manner which provides for a balanced flight when the primary section P is being driven by its motor M. The guide sleeve 21, a tubular straw-like member, is also mounted upon this main body section alongside a guide fin. This section 15 includes further, an abutment ring 25, this ring being placed within the tube at a depth sufiicient to permit a substantial portion of the cylindrical rocket motor M to be inserted into the trailing end of the body section, as will be further described.

An auxiliary body section 26 is adapted to be attached to the leading end of the body section 15 to extend its length for better balance during flight when the booster section is used. This auxiliary section 26 is preferably formed as a thin-walled cylindrical member having the same diameter as the main body section 15. A short cylindrical plug 27 is affixed to the rear end of the auxiliary section 26 and fits into the leading end of the main body section to connect the sections 15 and 26 together. The nose cone 16 is formed with a cylindrical base 28 which fits into the leading end of this auxiliary section 26. The plug 27 and base 28 are adapted to fit snugly into the ends of the body section 15 and auxiliary section 26 to hold the members together under normal use but to permit the members to be separated if necessary. Moreover, the sections 15 and 26 will separate when an ejection charge of the motor M fires, as will be described, and the plug 27 must fit into the leading end of section 15 with a releasable fit. The space within the auxiliary section 26 may be used to carry a payload, a message or the like, and it is preferably formed as a transparent cylindrical member when so used.

The arrangement for carrying a parachute in the forward portion of the body 15 will include a wadding 30 adjacent to the retaining ring 25 to prevent the gases ejected from the motor M from burning the parachute. Next, the parachute 23 will be suitably folded with the shroud lines 31 wrapped about it and secured to the leader line 32.

This leader line 32 also interconnects the auxiliary section 26 with the body section, and one end is suitably connected to the leading end of the main body section 15 as at 33 to extend thence and to an eyelet 34 at the trailing end of the plug and thence to the para- It follows that whenever the sections are separated as to be lowered by the parachute, the two sections 25 and 27 will be held together by the leader line 32.

The booster section B of the rocket model consists of the short, cylindrical body 18 which is a thin-wall shell having the same diameter as that of the main body section 15. The length is sufficient to retain the cylindrical rocket motor M for the booster and a short portion of the rocket motor M of the primary section, as hereinafter described. The guide fins 19 are arranged about this short body section in a radial array similar to the fin arrangement of the primary main section 25 so that when the sections are interconnected the fins of one may be arranged in alternating arrangement with respect to the fins of the other, or the fins may be formed so that the trailing edge of the guide fins 17 will abut against the leading edge of the guide fins 19 as by shaping the guide fins 19. This produces the effect of a single set of fins. In addition to the fins, this section B includes only an abutment ring 35 at its trailing end. This ring is adapted to hold the trailing end of a booster motor M, and it is to be noted that the inside diameter of this abutment ring is sufficiently large as to permit free movement of discharge gases from through it as from the motor it supports. Also, other means, not shown, can be used to secure this booster motor M in the section B, such as glue, friction tape and the like.

It is contemplated that both the primary section P and the booster section B of this rocket model will be driven by conventional cylindrical model rocket motors M and M of the common pyro-propulsion type which are practically standardized in length and diameter. It is further contemplated that these two motors M and M will be interconnected together in tandem and will also function to hold the primary section P and booster section B of the rockets together during the first phase of flight, as will be described.

The trailing rocket motor M is adapted to be carried in the body section of the booster. It is illustrated at FIG. 8 as being a tubular shell 37 having a shaped discharge nozzle 38 of heat resistant material at its trailing end. A driving powder charge 39 is compressed within this tube behind this nozzle, the powder being of a type which burns at a comparatively slow rate to eject a high velocity driving jet of gas from the nozzle for an appreciable time period. As the propellant powder charge 39 burns to the leading end of the motor under substantial pressure, the hot gas and particles of burning powder are directed forwardly, and this serves to separate the two motors and ignite the second motor.

This motor M is adapted to be carried at the trailing end of the primary section of the rocket, and it is formed as a shell 37 having a nozzle 38 at its discharge end, a driving charge of powder 39 within the body, and an explosive ejection charge 40 at its leading end. It also includes a slow-burning delay charge 41 between the powder 39 and the ejection charge 40 to provide for an appreciable time delay between the burning out of the driving charge 39 and the subsequent burning of the ejection charge 40. This delay action is to permit the primary rocket to coast upwardly to gain maximum height before the ejection charge 40 separates the body 15 and the auxiliary portion 26.

These motors M and M are fastened together in their tandem arrangement by wrapping a strip of tape 42 about the joint where the two rocket motors abut together as in the manner clearly illustrated at FIG. 7. It is contemplated that this tape 42 will be a material such as Scotch Tape or masking tape which can be torn apart or which will otherwise hold with a moderate force so that whenever the propellant charge 39 of the motor M burns to the forward end of the motor, the gas pressure will either sever the Scotch Tape 42 or pull one motor out of the embrace of the tape to separate the motor sections. This arrangement using ordinary Scotch Tape holds to motor sections together with sufficient tightness as to cause the rapid burning propellant charge 39 to positively ignite the powder charge 39 at the orifice 38 of the leading motor M as the motors separate.

The motors M and M are normally of a size which will fit within their respective body sections 18 and 15 with a comparatively loose sliding fit to allow for variations of size. However, in setting up the multi-stage rocket for flight, they must fit into the sections snugly to hold them together, and it is contemplated that the motors may be made to it snugly by simple wraps of tape about the shells 37 and 37. As illustrated at FIGS. 4 and 6, the length of the booster body is somewhat greater than the length of the motor M so that when in proper position it will extend into the body with its trailing end abutting against the retaining ring 35'. Accordingly, the tape wrap 42 connecting the sections M and M together may be formed to be adequate to hold the motors in position within this booster section. Two additional wraps 43 may be formed about the leading rocket motor M in position so that these wraps will extend into the main body section when the primary and booster sections of the rocket are put together as in the manner illustrated at FIG. 4. It follows that this simple arrangement will hold the two sections together with a proper degree of snugness which may be easily varied by more or less wraps of tape about the motors. It is also apparent that the Wraps 43 on the leading motor M may be easily formed to be sufficiently tight to cause effective separation of the auxiliary body portion 26 from the primary rocket body and the ejection of the parachute, rather than merely a rearward ejection of the rocket motor itself.

Considerable variations of this construction are possible without departing from the scope of the invention. The main features of the invention consist in the arrangement of the two rocket motors M and M abutted end to end Within the bodies of the booster section and the primary section, and to be held between the retaining rings 25 and 35. It is contemplated that this fit of the two sections shall be comparatively snug and that a substantial force of the propellant charge 39 will be required to separate the two sections, as by breaking or pulling loose from the tape 42. Accordingly, in lieu of placing the tape wrap 42 about the rocket motors, the same results can be obtained if a wrap of tape is effected about the abutting body sections 18 and 25 in a manner which is not herein illustrated, but which will obviously produce the same result as long as the ends of the motors M and M are held together.

Other variations of this arrangement are easily possible, and it becomes immediately apparent that a threestage model rocket can be built using a primary section P and two boosters B and B, as illustrated at FIG. 9. The bottom booster B will be the same as that heretofore described, while the intermediate booster B will consist of a cylindrical section 13' having guide fins 19, the same as the booster B, but no internal abutment ring. Three motors will be held together as a tandem group by tape wraps, as in the manner heretofore described.

A further simplification of the rocket model, to make a single-stage unit, is illustrated at FIG. 10. In this arrangement, only the primary section P is used, and it is shortened by removal of the auxiliary body portion 26 with the nose cone to being fitted into the leading end of the body section 15. This replacement is but a simple matter, and an eyelet 34' may be aflixed to the base 27 of the nose cone to connect with the leader line 32, as in the manner hereinbefore described.

We have now described our invention in considerable detail; however, it is apparent that those skilled in the art can build and devise other similar constructions and arrangements which are nevertheless within the spirit and scope of our invention. Hence, we desire that our protection be limited, not by the constructions illustrated and described, but only by the proper scope of the appended claims.

We claim:

1. In a model rocket having at least two separable stages, the combination comprising:

at least two separable rocket casing members;

a first pyropropulsive rocket motor member mounted within one of said casing members; a second pyropropulsive rocket motor member mounted Within the other of said casing members;

said casing members, and hence said first and second mot-or members, being arranged in end-to-end aligned relationship forming an interface between said casing members and an interface between said first and second motor members;

releasable coupling means provided at one of said interfaces to maintain said members in said aligned relationship;

said releasable coupling means including a strip of material at least partially surrounding said one interface, said strip having a portion thereof secured to the exterior of each of the aligned members forming said one interface;

said coupling means maintaining said members in said aligned relationship so long as said motor members are unignited;

said first motor member having means ignitable to thereby create a positive pressure at said one interface and to eventually ignite said second motor member;

said positive pressure serving as means to release said coupling means to thereby permit said casing members to separate from one another.

2. The combination defined in claim 1 wherein said strip is fabricated of frangible material and wherein said positive pressure ruptures said material, thereby effecting separation of said casing members.

3. The combination defined in claim 1 wherein said strip is adhesively secured to the exterior of each of said members forming said one interface and wherein said positive pressure causes said adhesive to release, thereby effecting separation of said casing members.

References Cited by the Examiner RICHARD C. PINKHAM, Primary Examiner.

L. I. BOVASSO, Assistant Examiner. 

1. IN A MODEL ROCKET HAVING AT LEAST TWO SEPARABLE STAGES, THE COMBINATION COMPRISING: AT LEAST TWO SEPARABLE ROCKET CASING MEMBERS; A FIRST PYROPROPULSIVE ROCKET MOTOR MEMBER MOUNTED WITHIN ONE OF SAID CASING MEMBERS; A SECOND PYROPROPULSIVE ROCKET MOTOR MEMBER MOUNTED WITHIN THE OTHER OF SAID CASING MEMBERS; SAID CASING MEMBER, SAND HENCE SAID FIRST AND SECOND MOTOR MEMBERS, BEING ARRANGED IN END-TO-END ALIGNED RELATIONSHIP FORMING AN INTERFACE BETWEEN SAID CASING MEMBERS AND AN INTERFACE BETWEEN SAID CASING OND MOTOR MEMBERS; RELEASABLE COUPLING MEANS PROVIDED AT ONE OF SAID INTERFACES TO MAINTAIN SAID MEMBERS IN SAID ALIGNED RELATIONSHIP; SAID RELEASABLE COUPLING MEANS INCLUDING A STRIP OF MATERIAL AT LEAST PARTIALLY SURROUNDING SAID ONE INTERFACE, SAID STRIP HAVING A PORTION THEREOF SECURED TO THE EXTERIOR OF EACH OF THE ALIGNED MEMBERS FORMING SAID ONE INTERFACE; SAID COUPLING MEANS MAINTAINING SAID MEMBERS IN SAID ALIGNED RELATIONSHIP SO LONG AS SAID MOTOR MEMBERS ARE UNIGNITED; SAID FIRST MOTOR MEMBER HAVING MEANS IGNITABLE TO THEREBY CREATE A POSITIVE PRESSURE AT SAID ONE INTERFACE AND TO EVENTUALLY IGNITE SAID SECOND MOTOR MEMBER; SAID POSITIVE PRESSURE SERVING AS MEANS TO RELEASE SAID COUPLING MEANS TO THEREBY PERMIT SAID CASING MEMBERS TO SEPARATE FROM ONE ANOTHER. 